Recently, Organic Light Emitting Diode (OLED) technology has gained rapid developments and become the most promising technology which may replace Liquid Crystal Displays (LCDs).
FIG. 1 shows a pixel array of an OLED display panel. The pixel array 100 includes a plurality of pixel points 110, each of which includes three subpixels 111 of three different colors which are arranged in a delta arrangement. When displaying images using such pixel array, the edge 200 of the displayed object will appear as unsmooth zigzags. In order to improve display effect, there are proposed the following two methods to reduce the zigzags which occur at edges of displayed objects.
FIG. 2 shows a first method: with a pixel point in the pixel array as a unit, the image signals to be displayed are filtered using a low pass filter so as to modify the brightness values of pixel points. This method can remove the zigzags at edges, and however, portions of the image where no zigzags occur become blurred because of filtering. Because the filtering is performed with a pixel point as a unit, the height D of the region at the edges of the displayed object where brightness values change gradiently is a total height of at least two pixel points, thereby resulting in blurring in edge portions of the object.
FIG. 3 shows a second method: the subpixels 111 which are in a region 300 which protrudes from the edges and has a relatively high brightness value are filtered using a low pass filter. However, such method needs to determine whether the subpixels 111 are located at edges of the object. Also, when the edges of the displayed object are white lines on a black background, such method will cause the white lines to become thinner. And when the edges of the displayed object are black lines on a white background, such method will cause the black lines to become thicker.